Water tube boiler or steam generator



Aug. 28, 1962 A. CLARKSON ET AL WATER TUBE BOILER OR STEAM GENERATOR 2 Sheets-Sheet l Original Filed Feb. 18

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ALICK CLAQKsoN Dotl/Aw W. MILLER 7 W7 '2??? Aug. 28, 1962 A. CLARKSON ETAL 3,051,146

WATER TUBE BOILER OR STEAM GENERATOR Original Filed Feb. 18, 1955 2 Sheets-Sheet 2 m AucK CLAEKSON DONALD W. MILLER .EZZZz United States Patent ()lfice 3,051,146 Patented Aug. 28, 1962 3,051,146 WATER TUBE BOILER R STEAM GENERATOR Alick Clarkson, Paul Spur, Ariz., and Donald W. Miller,

Midland, Tex., assignors to Vapor Heating Corporation, Chicago, 111., a corporation of Delaware Original application Feb. 18, 1955, Ser. No. 489,060, now Patent No. 2,998,807, dated Sept. 5, 1961. Divided and this application June 15, 1961, Ser. No. 117,404

13 Claims. (Cl. 122249) This invention relates to improvements in boilers or steam generators of the general class in which the water or other fluid to be heated or evaporated is passed through a plurality of substantially concentrically arranged tubular coils in heat exchange relation with the fire and hot gases within the boiler structure.

The present invention was originally disclosed in our co-pending application Serial No. 489,060, filed February l8, 1955, now Patent No. 2,998,807 of which the present application is a division.

A principal object of the present invention is to provide, in a boiler or steam generator of the general water coil type disclosed and claimed in our said co-pending application, certain improved constructions and arrangements of the Water coils, whereby the said coils may be connected in series relation and arranged one within another to define a fire chamber and associated annular passageways for the hot gases of combustion; the fire chamber and passageways have corrugated Walls and are so connected with each other as to provide a relatively long streamline flow path for the hot gases through the fire chamber and through the said annular passageways, whereby adequate turbulence for eflicient combustion, high thermal eificiency and operating economy is attained without excessive reverberation within the fire chamber and flow path of the hot gases.

Another object of the invention is to provide an improved boiler or steam generator of the above class having streamline gaseous flow and in which heating coils are so arranged that the incoming fluid to be heated will flow, for the most part, through the tubular coils in a direction opposite to the flow path of the combustion gases and thereby contact areas of the tubular coils of progressively increasing temperature, but in the final heating period of the fluid it will flow in series relation to the flow path of the flame and hot gases through the innermost coil constituting the fire chamber of the boiler. Accordingly, the fluid entering the system will first come intov heat transfer relation with areas of the coils which are heated by gases which have previously delivered up part of their heat, but are nevertheless sufficiently hot to present a high heat difierential. As the flow of fluid progresses through the system it comes into heat transfer relation with progressively hotter areas of the coiled tubes. Immediately before it leaves the system, it is caused to traverse the innermost coil wherein it is heated by the high temperature flame and gases in the fire chamber.

A further object is to provide a boiler or steam generator of the above class wherein the coils are so constructed as to provide a rigid compact structure as a whole so as to facilitate arrangement of the coils either horizontally or vertically, as may be desired, and wherein each coil includes a closed wall portion and an open Wall portion, the said closed wall portion of each coil being arranged in opposition to the open Wall portion of an adjacent coil whereby the hot gases passing radially between the convolutions of the open wall portion of one coil will come into wiping contact with the closed wall portion of an adjacent coil.

According to the present invention, there are three coils arranged in concentric relation and spaced apart to provide annular passageways leading from the end of the tire chamber remote from the ignition end thereof to the vent outlet. Each coil includes a portion formed with convolutions which are contiguous throughout their entire circumference so that the inner and outer surfaces of the closed portion of the coil will have a corrugated or sinuous configuration. The open Wall portion may include a group of convolutions arranged in axial alignment with the contiguous coils but are spread apart to provide radial passageways for the gases or may include a group of polygonal turns or convolutions which have engagement with each other at spaced locations and because of their polygonal configuration provide a series of passageways between the convolutions so that the hot gases have wiping contact with substantially the entire area of these convolutions. The said closed wall portions of the coils, because of their corrugated character, promote sutficient turbulence in the ignited gases both Within the fire chamber and in said annular passageways to insure efficient cobustion of a large volume of fluid fuel in relation to the size of the boiler structure.

A cylindrical sleeve surrounds in close relation to the polygonal convolutions of the intermediate coil so that the hot gases which wipe the inner surface of the closed wall portion of this coil are compelled to follow a circuitous path through the openings formed between the polygonal convolutions and thereby wipe substantially the entire area of these convolutions before passing into the annular passageway between the said intermediate coil and the outer coil of the srtucture. The outer coil is provided with a similar group of polygonal convolutions in the region near the vent pipe leading to the atmosphere so that the outgoing combustion gases are compelled to follow a circuitous heat exchange path through and around the polynal convolutions containing the cool incoming water, whereby practically all of the heat contained in the combustion gases are absorbed therefrom before the gases enter the vent pipe.

Other objects and advantages of the invention, not at this time enumerated, will become more readily apparent as the nature of the invention is better understood.

A preferred embodiment of the invention is shown in the accompanying drawings wherein:

FIG. 1 is a sectional view taken longitudinally and substantially centrally through a water tube boiler constructed in accordance with the principles of the present invention;

FIG. 2 is a sectional view taken substantially on line 22 of FIG. 1 looking in the direction of the arrows;

FIG. 3 is a sectional view taken on line 33 of FIG. 1 looking in the direction of the arrows;

FIG. 4 is an enlarged fragmentary section taken on line 44 of FIG. 2; and

FIG. 5 is a fragmentary sectional view taken on line 5--5 of FIG. 3.

Referring to the drawings: 10 designates the improved boiler structure as a whole including an outer casing or shell 11 having front and rear plates 12 and 13, respectively, both of which are suitably secured to the shell 11. The front plate 12 constitutes a support for a fire pot assembly 14 in which initial ignition of the fuel takes place. It may also constitute a support for a burner unit (not shown) by means of which a liquid or a gaseous fuel may be introduced into the fire pot 14. While the fuel is ignited in the fire pot 14, its combustion is normally completed within the boiler fire chamber. However, in the event of incomplete combustion within the fire chamber, the combustion of the partially ignited fuel may be completed after it passes out of the fire chamber and into surrounding passageways formed by the several coils. The fire pot 14 is of conventional design and comprises a cylindrical body 15 of refractory material such as fire clay ienclosed between annular casings 16, 17, the latter of which defines the fire pot opening or passage through which a preregulated mixture of fuel and .air is introduced into the fire chamber of the boiler. An exhaust conduit 18 communicates with the interior of the casing 11 near the rear end thereof. The boiler structure 14, in addition to the elements above described, includes three concentrically arranged, but spaced apart water coils 19, 20and 21, the innermost of which defines the fire chamber 22.

The coil 19 comprises a plurality of spiral convolutions 23 positioned along the inner face of the front wall 12 and serving to prevent the hot gas from impinging against the wall 12. The said spiral convolutions 23 connect with a large group 24 of closely wound turns or convolutions which are contiguous throughout their circumference and define a closed wall portion of the fire chamber 22. The closely wound coils 24 surround the fire pot 14, the latter of which serve to support a front end of the coil. The contiguous windings of the coil makes it practical to use a maximum number of convolutions in the side wall of the fire chamber and, therefore, increases the liquid volume contained in the fire chamber wall. The convexity of the tubes defining the side wall of the fire chamber provides the wall with a sinuous or corrugated configuration which increases the heat absorbing area thereof and also serves to promote turbulence so as to effect thorough intermixing of the fuel and air and thereby efiect more efficient combustion and also recurrent wiping of the hot gases against all parts of the fire chamber wall. The group 24 of contiguous convolutions connect with a small group 25 of convolutions at the end of the fire chamber remote from the fire pot 14. These convolutions are axially aligned with the group 24 but are spaced apart to provide radial passageways through which the hot gases are discharged from the'fire chamber 22.into an annular passageway 27 intervening between the innermost coil 19 and the intermediate coil 20. The spaced apart convolutions 25, it will be observed, presents substantially their entire area to the fire and gaseous products of combustion at a location near thedischarge end of the system so that the hot water or steam will be discharged at its maximum temperature. This high temperature discharge of the heated fluid is aided to a substantial extent by a series of radially arranged convolutions constituting a group 29. This group intervenes between the end convolution of group 25 and the outlet pipe 28. I The spiral turns of the group 29 of convolutions are partially embedded in and, therefore, supported by a body of. refractory. material 30 constituting a part of a header assembly 3 1 which, in turn, is supported by the discharge conduit 28 and the end wall 13. The ignited and partially ignited fuel impinges against the header 31 and the spiral group of turns 29 before passing through the radial passageways 26. In order to add rigidity to the convolutions of the spaced apart group 25, spacer blocks 32 may be fixed at suitable locations between the spaced apart convolutions. The said header assembly, in addition to the refractory material 30, includes a cup shaped shell 33 spaced from the end wall 13 and serving to retain the refractory material 30.

The intermediate coil 20 of the boiler includes a group 34 of contiguous polygonal convolutions which surround the inner coil 19 but are in spaced relation thereto, at the fire pot end of the boiler. The inner end of this group 34 of polygonal convolutions connects with a group 35 of contiguous cylindrical convolutions which provide a closed side wall portion of the coil 20 and extend beyond the header assembly 31 and connects with a group 36 of radially wound convolutions which overlie the marginal outer face portion of the header assembly 31. The individual turns of the group of convolutions 34 include four and one-half straight-away portions 37 and four arcuate portions 38. This construction presents an effective staggering of .the straight-away portions 37 relative to the straight-away portions of adjacent convolutions and thereby provide passages 39 for the combustion gases between the adjacent polygonal coils. Each polygonal coil has nine areas of contact, as at 40, where it crosses adjacent convolutions. Consequently, the coil 20, in effect, is composed of contiguous coils throughout its length, yet the coils 34, because of their polygonal configuration, provide the openings 39 for the flow of hot gases between the coils in a manner to wipe substantially the entire area of each convoltuion of said group 34.

The coil 20, it will be observed, is arranged with its contiguous cylindrical convolutions 35 arranged opposite the open wall group of convolutions 25 of the coil 19. Consequently hot gases pass through the open wall passages 26 of coil 19 and enter the said annular passage 27 existing between the opposed surfaces of the inner coil 19 and the intermediate coil 20. The hot gases within the annular passage 27 continue their turbulence and wiping action because of the opposed corrugated wall surfaces of the said passage. The hot combustion gases then pass through passages '39 existing between the convolutions 34 which, by virtue of their polygonal configuration, provide said passages as shown best in FIG. 4.

The hot gases, after passing through the openings 39 between the polygonal convolutions of group 34, pass into the annular space or channel 41 existing between intermediate coil 20 and the outer coil 21. A cylindrical baffie 42 surrounds a portion of this series of polygonal configurations at the junction thereof with the group 35 of cylindrical contiguous convolutions 35 so that the hot gases in the annular passageway 27 are compelled to pass through circuitous passages 39 on their way to their entrance into an annular passage 41 between the intermediate coil 20 and the outer coil 21.

Referring now to the construction of the outer coil 2i1: It is similar to the construction of the intermediate coil 20 in that it includes a series of closely wound cylindrical convolutions 43 constituting a closed outer side wall of the annular passage 41, and a group of polygonal convolutions 44. This coil, however, is of shorter length than the intermediate coil and is arranged in a reverse position in respect thereto so that the closed wall portion 43 of the outer coil is positioned opposite to the open wall portion 34 of the intermediate coil and the open wall portion of the group 44 of the polygonal convolutions of the outer coil are opposite the contiguous cylindrical convolutions 35 of the intermediate coil 20. Each polygonal convolution of group 25 includes four and one-half straight-away portions 45' (shown best in FIG. 2) and connect with arcuate portions 46. All of the polygonal coils have contact with adjacent coils at the several points 47. The said straight-away portion 45 and the arcuate portions 46 of adjacent coils are, in effect, offset in staggered relation to each other so that the passages 48 provided thereby for the hot gases will also have a like staggered relationship.

The connections of the several coils in series relationship so that the water or other fluid being heated will flow through the coils in a manner hereinbefore described is attained by connecting the water .inlet pipe.49.with the outer coil 21 at the end thereof which is remote from the fire pot 14. The inner end of the coil 21 connects with the inner end of the coil '20 and the outer end of the coil 20 is connected through a by-pass conduit 50 leading to the inlet end of the innermost coil 19 at its inner end. The extreme outer end of coil 19 connects with the outlet pipe 28 whereby the hot water or steam, as the case may be, will bedischarged at its maximum temperature and at the region of the fire chamber where the hot combustion gases leave the said chamber and pass .into the annular passageway 27.

We claim:

1. A boiler or steam generator including a plurality of serially connected tubular coils for containing liquid to be heated or vaporized and arranged one within another in spaced apart relation to provide an annular passageway between adjacent coils, the innermost coil of which constitutes a fire chamber and comprises a group of convolutions forming a closed side wall portion of the fire chamber at one end thereof and a group of spaced apart convolutions at the other end thereof providing gas discharge openings communicating with the surrounding annular passageway between the said innermost coil and the next adjacent coil, whereby the combustion gases follow a streamline flow path through the fire chamber and said surrounding annular passageway, and said next adjacent coil comprises a plurality of axially aligned groups of convolutions one of which is composed of a series of contiguous convolutions providing a closed wall portion arranged opposite the gas discharge opening of the fire chamber, and another group is composed of contiguous convolutions each of which has a series of portions ofiset radially relative to adjacent convolutions at circumferentially spaced locations to provide a series of discharge openings located opposite the closed side Wall portion of the fire chamber.

2. A boiler or steam generator according to claim 1 wherein the said group of contiguous convolutions having radially ofiset portions have contiguous contact with adjacent convolutions at spaced location only and the said offset portions are located between the said points of contact.

3. A boiler or steam generator according to claim 2 wherein each convolution of the group having radially oflset portions are of polygonal convolutions including in each case a series of straight-away portions the ends of which are connected in series relation by arcuate sections which constitute said ofiset portions.

4. A boiler or steam generator according to claim 3 wherein the straight-away portions and arcuate connection sections are arranged in staggered relation relative to like portions of adjacent convolutions.

5. LA. boiler or steam generator according to claim 4 wherein a circular baffle surrounds the other surface of a portion of said convolutions having said radially olfset portions, whereby hot combustion gases are compelled to follow an inwardly and outwardly circuitous path between the adjacent convolution in the region of said battle.

6. A boiler or steam generator according to claim 1 wherein a third coil is provided with a group of contiguous convolutions providing a closed wall opposite the discharge openings of the last mentioned coil and a second group of contiguous convolutions each of which has a series of portions oifset radially relative to adjacent convolutions at circumferentially spaced apart locations to provide a series of discharge openings located opposite the closed side wall of said last mentioned coil, a casing enclosing all of said coils and formed with a vent stack in the region of the last mentioned outlet openings, said casing serving as a baflie to direct a portion of the gases through a circuitous path defined by the olfset portions defining said last mentioned discharge openings.

7. A boiler or steam generator according to claim 6 wherein each convolution of the group having radially offset portions are of polygonal configuration including in each case a series of straight-away portions the ends of which are connected in series relation with arcuate sections which constitute said offset portions.

8. A boiler or steam generator according to claim 1 wherein an end wall is provided for closing the ends of said annular passageways at the front ends of the coils and wherein the innermost coil includes a series of radially extending spiral convolutions positioned adjacent the front end wall of the structure and serving to prevent overheating of said end wall.

9. A boiler or steam generator according to claim 8 wherein the end of the fire chamber adjacent said group of spaced apart convolutions of the innermost coil is closed by means of a header of refractory material and the said innermost coil is provided with a series of radially arranged spiral convolutions which connect with an outlet pipe and are partially embedded in said refractory material of said header, whereby the flames and hot combustion gases within the fire chamber impinge against said partially embedded convolutions so that the fluid therein will be discharged at maximum temperature.

10. In a water tube boiler or steam generator of the character described, in combination, an outer casing presenting an inner cylindrical wall, a plurality of helically wound tubular coils disposed within said casing and arranged one within another to provide inner, outer and intermediate coils connected in series and the said intermediate coil cooperating with said inner coil to define an annular space surrounding the inner coil and said outer coil cooperating with said intermediate coil to define a second space surrounding the intermediate coil, an end wall structure for closing one end of the inner coil and defining, in combination with said inner coil, a combustion chamber, a firepot projecting into the other end of said inner coil for supplying combustible materials to said combustion chamber, each of said coils being comprised of two groups of helical turns, one of which has adjacent turns provided with opposed surfaces which are separated from each other to provide open spaces for the passage of combustion gases therethrough and the other of which has its adjacent turns arranged in substantial coextensive contact, the groups of dissimilar characteristic in the three coils being directly opposed to each other in radial opposition.

11. In a water tube boiler or steam generator of the character described, the combination set forth in claim 10 wherein the group of helical turns of the inner coil whose adjacent coil provides said open spaces is disposed within the casing at the rear thereof.

12. In a water tube boiler or steam generator of the character described, the combination set forth in claim 11 wherein said fluid inlet and said fluid outlet connect with the rearmost helical turn in the outer and inner coils respectively and in which the rearmost helical turn of the intermediate coil is connected to the foremost helical turn of the inner coil by a length of by-pass tubing.

-13. In a water tube boiler or steam generator of the character described, the combination set forth in claim 11 wherein all of the helical turns of the intermediate and outer coils are arranged in longitudinal contiguity.

References Cited in the file of this patent UNITED STATES PATENTS 1,814,605 Mayr a July 14, 1931 2,645,210 Harris et a1. n July 14,1953

2,718,217 Walter Sept. 20, 1955 2,998,807 Clarkson et a1. Sept. 5, 1961 FOREIGN PATENTS 461,733 Canada Dec. 13, 1949 985,262 =France Mar. 7,1951 

